1. Field of the Invention
The present invention relates to an uninterruptible power supply(UPS) system, and more particularly to an improved uninterruptible power supply system advantageously including a transformer for increasing or decreasing voltage obtained from an inverter and a bypass line to a predetermined level, another transformer for decreasing voltage thereof, and an integrated transformer having a reactor.
2. Description of the Conventional Art
Conventionally, almost all applied electronic instruments might be damaged by abrupt interruptions in power supply. In an attempt to prevent those kinds of damage, uninterruptible power supply(UPS) systems are usually used.
Referring to FIG. 1, a conventional uninterruptible power supply system includes a converter 10 for convening three-phase alternating current voltage into direct current voltage, a battery 20, connected to a ground, for charging direct current voltage converted at the converter 10, an inverter 30 for modulating direct current voltage outputted from the converter 10 or the battery 20, an LC filter 40 for shaping waveforms of voltage modulated by the inverter 30, a first switch 50 for supplying an output voltage to an externally connected electrical load such as an electronic appliance by selectively switching the flow of the output voltage of the LC filter 40, a second transformer 60 for decreasing the voltage of the three-phase alternating current voltage inputted through a bypass line, and a second switch 70 for supplying output voltage to the externally connected load by selectively switching the flow of the output voltage of the second transformer 60.
The LC filter 40 includes a reactor 41 for shaping waveforms of voltage outputted from the inverter 30, a first transformer 43 for increasing the voltage outputted through the reactor 41, and a condenser C1 for shaping waveforms of the voltage increased by the first transformer 43.
Referring to FIG. 3, the reactor 41 includes a first inductor L1 and a second inductor L2 in which the output line the inverter 30 are wound onto the core 42 in series.
Referring to FIG. 2, the first transformer 43 and the second transformer 60 output a voltage V2 of the secondary coil which varies with the winding ratio of the primary and secondary coils which are wound onto the core 44.
The detailed operation of the uninterruptible power supply system according to the present invention will now be explained.
To begin with, the converter 10 receives the three-phase alternating current voltage of 220 V, converts the three-phase alternating current voltage into a direct current voltage and then outputs the direct current voltage to the battery 20 and the inverter 30.
Thereafter, the battery 20 charges the inputted direct current voltage and outputs the direct current voltage into the inverter 30. The inverter 30 modulates the direct current voltage and outputs a single-phase alternating current voltage of 80 V. The single-phase alternating current voltage of 80 V is inputted into the first transformer 43 through the first and second inductors L1 and L2. Here, the first transformer 43 increases the inputted single-phase alternating current voltage up to 110 V.
In addition, the waveforms of the alternating current voltage which is increased by the first transformer 43 are converted into a sine waveform by the LC filter 40 formed of the inductors L1 and L2 and the condenser C1.
Thereafter, the first switch 50 applies the voltage outputted from the LC filter 40 to the electrical load by selectively switching the flow of the voltage.
Meanwhile, the three-phase alternating current voltage of 220 V is also inputted into the second transformer 60 through the bypass line. Here, the second transformer 60 decreases the 220 V input voltage to 110 V and inputs the decreased voltage into the second switch 70. Therefore, when any malfunction occurs during use of the uninterruptible power supply system, the first switch 50 is cut off and then the second switch 70 supplies the voltage of 110 V to the electrical load.
However, according to the conventional uninterruptible power supply system, the first transformer for increasing the output voltage of the inverter 30, the reactor 41 for shaping the waveforms of the output voltage of the inverter 30 into a sine waveform, and the second transformer 60 are separately disposed from one another therein, so that a simple and light construction thereof cannot be obtained, and in addition in assembling the system, many wiring lines are needed.